Hansen paper emphasizes importance of retention and expansion of nuclear power for health and climate reasons
|Mean number of deaths prevented annually by nuclear power, 1971-2009. Credit: ACS, Hansen et al. Click to enlarge.|
A new study by James Hansen and Pushker Kharecha from the NASA Goddard Institute for Space Studies and Columbia University Earth Institute has found that global nuclear power has prevented an average of 1.84 million air pollution-related deaths and 64 gigatonnes of CO2-equivalent (GtCO2-eq) greenhouse gas (GHG) emissions that would have resulted from fossil fuel burning. The estimated human deaths caused by nuclear power from 1971 to 2009 were far lower than the avoided deaths: 4,900, or about 370 times lower than the result for avoided deaths.
Projecting ahead, on the basis of global projection data that takes into account the effects of the Fukushima accident, Hansen and Kharecha also calculated that nuclear power could additionally prevent an average of 420,000−7.04 million deaths and 80−240 GtCO2-eq emissions due to fossil fuels by mid-century, depending on which fuel it replaces. Large-scale expansion of unconstrained natural gas use would not mitigate the climate problem and would cause far more deaths than expansion of nuclear power, according to their analysis, which is published in the ACS journal Environmental Science & Technology.
...our results underscore the importance of avoiding a false and counterproductive dichotomy between reducing air pollution and stabilizing the climate, as elaborated by others. If near-term air pollution abatement trumps the goal of long-term climate protection, governments might decide to carry out future electric fuel switching in even more climate-impacting ways than we have examined here. For instance, they might start large-scale production and use of gas derived from coal (“syngas”), as coal is by far the most abundant of the three conventional fossil fuels. While this could reduce the very high pollution-related deaths from coal power, the GHG emissions factor for syngas is substantially higher (between ∼5% and 90%) than for coal, thereby entailing even higher electricity sector GHG emissions in the long term.
In conclusion, it is clear that nuclear power has provided a large contribution to the reduction of global mortality and GHG emissions due to fossil fuel use. If the role of nuclear power significantly declines in the next few decades, the International Energy Agency asserts that achieving a target atmospheric GHG level of 450 ppm CO2-eq would require “heroic achievements in the deployment of emerging low-carbon technologies, which have yet to be proven. Countries that rely heavily on nuclear power would find it particularly challenging and significantly more costly to meet their targeted levels of emissions.”
Our analysis herein and a prior one strongly support this conclusion. Indeed, on the basis of combined evidence from paleoclimate data, observed ongoing climate impacts, and the measured planetary energy imbalance, it appears increasingly clear that the commonly discussed targets of 450 ppm and 2 °C global temperature rise (above preindustrial levels) are insufficient to avoid devastating climate impacts; we have suggested elsewhere that more appropriate targets are less than 350 ppm and 1 °C. Aiming for these targets emphasizes the importance of retaining and expanding the role of nuclear power, as well as energy efficiency improvements and renewables, in the near-term global energy supply.—Kharecha and Hansen
To estimate historically prevented deaths and GHG emissions, the team used data for global annual electricity generation by energy source from 1971 to 2009, then applied mortality and GHG emissions factors—deaths and emissions per unit electric energy generated, respectively—for relevant electricity sources). For the projection period 2010−2050, they based their estimates on post-Fukushima nuclear power trajectories given by the UN International Atomic Energy Agency (IAEA).
For the historical period 1971−2009, they assumed that all nuclear power supply in a given country and year would instead have been delivered by fossil fuels (specifically coal and natural gas).
For the projection period 2010−2050, they calculated human deaths and GHG emissions that could result if all projected nuclear power production is canceled and again replaced only by fossil fuels. The authors note that some or most of this hypothetically canceled nuclear power could be replaced by power from renewables, which have generally similar impact factors as nuclear. Results for the projection period should ultimately be viewed as upper limits on potentially prevented impacts from future nuclear power, the authors suggested.
(Dr. Hansen, a long-time advocate for action to mitigate anthropogenic climate change, is retiring from NASA to enable him to increase his activism.)
Pushker A. Kharecha and James E. Hansen (2013) Prevented Mortality and Greenhouse Gas Emissions from Historical and Projected Nuclear Power. Environmental Science & Technology doi: 10.1021/es3051197